/* This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 *
 * http://www.gnu.org/copyleft/gpl.html
 */

package net.sf.l2j.util;

import java.net.InetAddress;
import java.nio.channels.SocketChannel;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map.Entry;

import org.mmocore.network.IAcceptFilter;

/**
 * Formatted Forsaiken's IPv4 filter [DrHouse]
 * 
 * @Reworked by Adryan
 * 
 */
public class IPv4Filter implements IAcceptFilter, Runnable {
	private HashMap<Integer, Flood> _ipFloodMap;
	private static final long SLEEP_TIME = 5000;

	public IPv4Filter() {
		_ipFloodMap = new HashMap<Integer, Flood>();
		Thread t = new Thread(this);
		t.setDaemon(true);
		t.start();
	}

	/**
	 * 
	 * @param ip
	 * @return
	 */
	private static final int hash(byte[] ip) {
		return ip[0] & 0xFF | ip[1] << 8 & 0xFF00 | ip[2] << 16 & 0xFF0000
				| ip[3] << 24 & 0xFF000000;
	}

	protected static final class Flood {
		long lastAccess;
		int trys;

		Flood() {
			lastAccess = System.currentTimeMillis();
			trys = 0;
		}
	}

	public boolean accept(SocketChannel sc) {
		InetAddress addr = sc.socket().getInetAddress();
		int h = hash(addr.getAddress());

		long current = System.currentTimeMillis();
		Flood f;
		synchronized (_ipFloodMap) {
			f = _ipFloodMap.get(h);
		}
		if (f != null) {
			if (f.trys == -1) {
				f.lastAccess = current;
				return false;
			}

			if (f.lastAccess + 1000 > current) {
				f.lastAccess = current;

				if (f.trys >= 3) {
					f.trys = -1;
					return false;
				}

				f.trys++;
			} else {
				f.lastAccess = current;
			}
		} else {
			synchronized (_ipFloodMap) {
				_ipFloodMap.put(h, new Flood());
			}
		}

		return true;
	}

	public void run() {
		while (true) {
			long reference = System.currentTimeMillis() - (1000 * 300);
			ArrayList<Integer> toRemove = new ArrayList<Integer>(50);

			synchronized (_ipFloodMap) {
				for (Entry<Integer, Flood> e : _ipFloodMap.entrySet()) {
					Flood f = e.getValue();
					if (f.lastAccess < reference)
						toRemove.add(e.getKey());
				}
			}

			synchronized (_ipFloodMap) {
				for (Integer i : toRemove) {
					_ipFloodMap.remove(i);
				}
			}

			try {
				Thread.sleep(SLEEP_TIME);
			} catch (InterruptedException e) {

			}
		}
	}

}